1. Technical Field
The present disclosure relates to optical networks, and more specifically relates to a method and apparatus for generating reachability matrices to aid in routing across multiple vendor domains in an optical network.
2. Brief Description of the Related Art
With technology evolution and industry consolidation, a large carrier's core Dense Wavelength Division Multiplexed (DWDM) optical network may include several DWDM subsystems from different vendors using different technologies, such as wavelengths of differing rates to transport a variety of end-to-end circuits or signals, such as, but not limited to, SONET (e.g., rates OC-48, OC-192, or OC-768) or Ethernet (e.g., 1, 10, or 100 Gigabit Ethernet), or ITU OTN rates (e.g., ODU-0 through ODU-4), and optical reachability parameters. However, a customer requesting an end-to-end high speed connection should not need to be aware of the underlying heterogeneous subsystems. For example, a user requesting a connection between New York City and San Francisco is only concerned with the connectivity and the requested bandwidth or capacity being satisfied by the connection. It is the carrier's responsibility to optimize connection routing in its own heterogeneous network to save cost and ensure high network availability. Traditional point-to-point DWDM subsystems normally support 2.5 Gb/s per wavelength. Most recent ROADM (Reconfigurable Optical Add-Drop Multiplexer)-based subsystems can support higher rate wavelengths.
In DWDM networks, the quality of a signal degrades due to physical impairments that accumulate along its path. This signal degradation may lead to an unacceptable bit-error rate (BER). Hence, after a certain impairment threshold, the signal needs to be regenerated in order to regain its original quality. In practice, signals are regenerated on a per-wavelength basis and not on a per-fiber basis using an Optical-Electrical-Optical (OEO) regenerator. This signal path limitation is referred to as the reachability limitation. Different vendors may apply different technologies to handle these impairments and use different fiber parameters or formulas to judge whether a path is reachable or not. There are no common parameters or formulas to calculate the BER of a path over multiple subsystems. In fact, the reachability parameters or formula are vendor-proprietary property, and thus not publicly available. These parameters and formulas are usually built in each vendor's subsystem planning tool.